Carburetor for internal-combustion engines



Jan. 22, 1929. 1,699,647

" I. R. zmamacwm CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed April 9, 1925 dizzy/rays described ISIIDIBJU RUDRTGUEZ ZARRAUTNA, OF VALLADOTJID, SPAIN.

. CARIB'UL'trETlDIft TUltt TNTERNAL-UUMBUSTTON ENGINES.

application filed .llpril aiaaa Serial Ito. 21,890, and. in Great Britain December 10, 19%.

- lit is well known that in aviation motors the considerable variations in the fuel feed due to changes in altitude which result in corresponding variations in the proportions a of the combustible mixture-supplied to the engine, and that with any ordinary carburetor not provided with a device to -annul or compensate such variations, the motor works irregularly, is deficient in power or extravagant ii the consumption of fuel.

The primary object of the present invention is to provide a carburetor for aviation motors with means whereby the proper proportions of the constituents of the combusl5 tible mixture can be maintained with changes of altitude, but the invention is not restricted to aviation motors, and can also be applied usefully to land or marine internal combustion engines. which are over-compressed or an over-charged andare liable to show irregularities in working.

' According to the present invention constanc in the proportions of the fuel mixture is maintained for diderent altitudes by means of a valve device whereby the supply of air designed'that while rotation in one direction through a varying angle ed'ects the necessary compensation for did'erent altitudes at moderate heights of flight, rotation in the re-, verse direction provides similar compensation over a zone of comparatively great altitudes, and to enable the pilot to make the appropriate adjustment of the valve mechanically in either zone the levercan be arranged to be shifted from one position to another 40 with respect to the valve spindle, so that the direction of movement of the valve lever to compensate for increasing. altitude in either zone will be the same for both zones. say from left to right, andsimilarly for decreasing at altitude. i

The invention will'be more particularly with reference to carburetors of the'type described in the specifications of British Patents Nos. 127579, 153506 and to 20247 2 granted to the present applicant, but

it can be applied with suitable modifications to any ordinary carburetor.

v in the accompanying drawings,which are merely diagrammatic. Fig. 1 represents a ver 5 tical section of a carburetor embodying the invention, and Figs. 2, 3, l, 5, 6 and 7 represent diflerent working positions of the man-v ually operated control valve.

As shown in Fig. l, A; is the engine throttle, B the-main air inlet and C the main min ing chamber. A tube D, leads from the main air supply to a passage controlled by a valve the primary mixing chamber H. The valve F also controls a passage ll leading to the interior of the fuel reservoir J the level of which is maintained constant by suitable means, such as the usual float feed, and which supplies the main fuel orifice K. The idling or slow speed nozzle L is provided in a tube M arranged concentrically within the primary air supply pipe G and depending into the primary mixing chamber. A pipe N bypasses the valve F and connects the primary air tube D with the tube M at a point beyond the slow speed nozzle L and thence with passages O, P leading to the main mixing chamber C on opposite sides of the throttle A. The inlet end of passage P which leads to the engine side of the throttle is controlled by suitable means, such as a screw valve Q. The primary mixing chamber leads to a perforated diifusion tube R which extends transversely across the main air supply passage B.

For low speed operation, the throttle A is closed asshown in Fig. 1, leaving the adjustable passage P open to the engine intake. The suction of the motor induces a flow of air through pipes D, N, M and passage 0 to passage P. and also draws liquid fuel from the cgltllflbel' H through pipe to feed'the nozz e When the throttle is opened thechamber becomes subject to the suction of the motor through the perforated didusion pipe R. During acceleration the chamber is emptied of fuel and thereafter the fuel from the tanlr .l issuing through the orifice mixes with the air supplied through tube G, forming an emulsion rich in liquid fuel. ere is a second admixture of air with this emulsion within the diffusion tube R and a further admixture of air when the fuelmixture emerges from the tube R.

The operation of the engine produces a high velocity of air entering the intake B and this pressure applied to theface of the tube next the open end of the intake causes some of the air to enter and pass throu h the tube as the opposite face of this tube is subject to suction which edects a reduced pressure. This results in a suction within the tube and thence to a pipe Gr opening into int and consequent feed of fuel from the chamber H which after its emission from the tube is further mixed with air at the portion C of the intake next-the throttle.

\Vith such a carburetor duly dimensioned for a given type of motor, the latter would be supplied with a mixture of definite proportions so long as .the altitude remains unchanged, and this definite proportion can be maintained at different altitudes provided the influx of air to the primary mixing chamber and the pressure in the fuel reservoir can be quickly and appropriately varied, and this is what is sought to'be done by the present-.im

' vention in the simplest and most eflicacious manner by means of the valve F which controls the air supply through pipe G to theprimary mixing chamber H and also, through duct I, the pressure on the surface of the fuel in tank J. v

The valve F, as shown in the drawings, is of the character of'a ported rotary sleeve valve having two solid orpbturating parts F, F

mounted in the interspace between two fixed ported sleeves S, T, which are interposed be tween the pipes E, G, and I, as shown in Fig. 1. The obturator portion F has a radial port F of small cross section.

The rotary valve is actuated by means of a lever U secured to the valve spindle in such a manner that it can be readily shifted from one angular position with respect to the spindle', for example that shown in Figs. 2, 3 and 4, to another angular position such as shown in Figs. 5, 6 and 7. For one zone of altitudes the lever is secured on the spindle in the first position and for a higher zone of altitudes it is removed from its position in Figure 2 and ap lied in the second position of Figure 5, the o ject being to preserve the same direction of movement of the lever to compensate for increasing altitudes in both zones.

For ordinary flying altitudes in which it is not necessary to provide a great range of compensation, the lever is .fixed in the position shown in Figs. 2 to 4 and as the altitude increases it is shifted towards the right from the position of Fig. 2 through intermediate positions to the position shown in Fig. 4. With the valve in the position shown in Fig. 2 the obturator F blocks the inlet of the tube G with the exception of the aperture F which is provided tofacilitate acceleration, whilst the primary air supply tube E and the passageI leading to the constant level fuel reservoir J are left open, with the result that the fuel surface is subjected to the same ressure as the main air inlet B of the car uretor. This is the position of the valve when the motor in working on the ground level or without correction. As the valve is rotated to-- wards the position of Fig. 3 the obturator F begins to uncover the inlet of tube G so as to permit the air to pass more freely through the tube G into the primary mixing chamber open, while the passage I leading to the fuel tank is closed but for the aperture F thus reducing the pressure on the surface of the fuel in the tank. This is the position of maximum correction for the first zone of comparatively low altitudes.

It will be seen that in the first of these three positions the supply of air to the primary mixing chamber is restricted to a maximum degree, while the effective pressure of the fuel in the main orifice K is a maximum.

' position for the zone of high altitudes and the valve is rotated in the opposite direction by the pilot moving the lever in the same absolute direction as before, the outlet of pipe E is reduced, while the inlet of pipe G is opened, as shown in Fig. 6, and consequently the effective pressure in the main orifice K is reduced on both accounts, while the air supply to the primary mixing chamber is increased. When this movement of the valve is continued to the position shown in Fig. 7, the pipe E is entirely blocked by the obturator F whilst the pipes G and I remain open, with the result that the efiective pressure in the main orifice K is nil and maximum compensation obtalilid, as no mixture will beunder pressure to I NVhatever position of the valve, even in the position shown in Fig. 7, there is no interference with the operation of the slow running jet, so that the motor can always rotate with reduced admission or opening of the control valve.

With the parts in the position stated there is no direct air feed to the reservoir chamber and during slow speed running the air is fed by the by-pass N into the tube M which receives its fuel from the chamber H, and there is air admitted from the tube B when the throttle valve is closed. Under these conditions there is a feed of fuel by gravity from the reservoir J to the primary mixing chamber H.

While the .invention has been described with reference to its use with aviation motors, it can also be applied beneficially to supercharged surface motors, such as high speed racing motors. 1

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In a carburetor, the combination with a fuel reservoir and a primary mixing chamber having a liquid fuel feed from the reservoir, of an air intake communicating with said reservoir and chamber, means for conjointly regulating the intake olair by separate connections to the reservoir and chamber, a feed from said chamber comprising a nozzle disposed in the air intake and operable by the passage of air therethroiigh, and a separate low speed fuel passage extending from said chamber to the intake separate from the nozzle feed.

2. In a carburetor, the combination with a fuel reservoir and a primary mixing chamher having a liquid fuel feed from the reservoir, of an air intake communicating with said reservoir and chamber, means for conjointly regulating the intake of air by separate connections to the reservoir and chamber, and a perforated tube communicating with said chamber and extended across the air intake to receive the pressure therein upon its perforated face next the open end of the intake, whereby a fuel feed from the chamber and opposite face of the tube to the intake is effected.

In a carburetor, the combination with a fuel reservoir and a primary mixing chamber having a liquid fuel feed fromthe reservoir, of an air intake, a conduit extending therefrom and having separate connections with said reservoir and chamber, and a rotary valve disposed in said conduit to conjointly control the air pressure in said connections to the reservoir and chamber. said valve having a portion of its solid wall provided with a reduced opening adapted to communicate with either the reservoir or the primary mixing chamber.

4. In a carburetor, the combination with a fuel reservoir and a primary mixing chamber carrying a body of liquid fuel, of an air intake, a conduit extending therefrom and having separate connections with said reservoir and chamber, a rotary valve disposed in said conduit to conjointly control the air pressure in said connections to the reservoir and chamber, a throttle valve in said intake, and av feed tube disposed in the intake and connuunicating with said chamber.

in a carburetor, the (OilllJilltLtlOll with a fuel reservoir and a primary mixing chamber carrying a body of liquid fuel, of an air intake, a conduit extending therefrom and having separate connections with said reservoir and chamber, a rotary Valve disposed in said conduit to conjointly control the air pressure in said connections to the reservoir and chamber, a throttle valve in said intake, a feed tube disposed in the intake and communicating with said chamber. a feed connection extending from said chamber to a position at the intake side of the throttle valve, and a bypass connection from the air conduit to the last named feed connection.

6. In a carburetor, the combination with a fuel reservoir and a primary mixing chamber, of an air intake, a conduit extending therefrom and communicating with said reservoir and chamber, and a rotary valve disposed in said conduit to conjointly control the air pressure in the reservoir and chamber,

said valve being operable in one direction for one zone of operation and in an opposite direction for a diflerent zone of operation.

7. An apparatus as defined in claim 3 wherein the control valve is provided with an operating handle shiftable from one angular position upon the valve spindle to another angular position sothat the adjusting move ment of the lever for either range of adjustment will be in the same direction.

In testimony whereof I have signed my name to this specification.

ISIDRO RODRIGUEZ ZARRACINA. 

